Surface finish gauging device



G. W. GRAY SURFACE FINISH GAUGING DEVICE Filed OC'C. 24, 1947 Nov. 25, 1952 Patented Nov. 25, 1952 UNITED STATES PATENT OFFICE SURFACE FINISH GAUGING DEVICE Gene W. Gray, North Hills, Pa.

Application October 24, 1947, Serial No. 781,801

(Cl. i3- 37) 12 Claims.

This invention relates to gauging devices and more particularly to gauging devices operated or controlled by means of a flow of air or other' uid.

One object of the invention is the provision of a gauging device for gauging surface finish in Which variations in fluid iilow between the surface to be gauged and a smooth work gauging surface are employed for measuring surface finish, yielding means being interposed between the gauging surface and the work head that carries the gauging surface so that the general contour or curvature of the surface gauged will be accommodated by the gauging surface.

Another object is the provision of a gauging device of the character mentioned, in which the gauging surface may be applied with a predetermined pressure to the surface to be gauged.

Another object is the provision of a gauging device for checking surface fini-sh, having a protecting sleeve that normally .protects the gauging surface.

Another object is the provision of a flow gauging means having an automatically oper-able valve movable in accordance with changes in pressure for amplifying operation of the iiow gauging means.

Another object is the provision of a gauging device adapted for connection to a source of fluid pressure and embodying a flow gauging means having a member responsive to fluid oW and a pressure chamber having a discharge opening, a relief valve, and a valve automatically operable in accordance with the pressure in the pressure chamber for controlling the ilow of fluid from the gauging means to the relief passage and so arranged that very small changes in fluid flow from the .pressure chamer to a suitable gauging orifice greatly amplify the changes in fluid flow that take place through the flow gauging means.

Other objects and advantages of the invention will be apparent from the following description, the appended claims, and the accompanying drawing, in which Fig. 1 is a front elevation of a gauging device embodying the present invention;

Fig. 2 is a vertical section of the amplifying valve, taken on the line 2-2 of Fig. 1;

Fig. 3 is a vertical sectional view on the line 3-3 of Fig. l showing the Work head which is applicable to the work for checking surface finish;

Fig. 4 is a sectional view of the lower portion of the work head shown in gauging position on a workpiece;

Fig. 5 is an end view of the amplifying valve housing; and

Fig. 6 is a detail showing the relief valve guide.

Referring more particularly to the drawing in which the same reference numerals have been applied to the like parts in the several views, I generally designates the frame of a flow gauging means adapted for connection through conduit II and an automatic pressure regulator I2 to a source of fluid under pressure. The factory air line may be used as a source, the pressure regulator I2 supplying air under controlled pressure through the conduit or pipe II to the lower side of a tapered flow tube I3 having an indicator or float I4. The passage through the tube I3 increases in size as the tube extends upwardly so the height of the float I4 indicates the rate of flow through the tube. The upper end of the tube is connected to a coupling I5, see Fig. 2, adjacent the lower end of the housing I0. The flow path from the factory air line connection to the coupling I may correspond to the arrangement described in U. S. Patent 2,254,259, although it should be understood that the flow gauging means may be of any suitable character.

Mounted on the coupling I5 is a valve housing II having valving which greatly amplifies the change in the rate of iiuid flow through the coupling I5 as changes take place in the iiow through the connection I8. The connection I8 may lead to any suitable gauging nozzle or nozzles the flow through Which is to be gauged and insofar as concerns the valving arrangement about to be described, it is to be understood that the invention is not limited to the checking of surface finish nor to the particular details of the valve itself. In the particular form of the invention illustrated however, the connection I8 is connected to a flexible conduit I9 leading to a tubular connection on a work head 2I which will be presently described.

The valve housing I1 is provided with an inlet passage 23 in communication with a passage 24 having branch passages 25 and 26, passage 28 communicating with a pressure chamber 21. A cylindrical passage 28 in the housing I1 forms an annular Wall partially defining the pressure chamber 2l, and a piston 29 slidable in the pase sage 28 forms a movable upper wall of the pressure chamber. The lower wall of the pressure chamber is formed by the plug 30 threaded in the threaded passage 3| in the housing. A sealing washer 32 prevents loss of fluid past the threaded connection. The plug 30 has a central passage 3 I leading to the connection I8, through which fluid' coming to the pressure chamber from branch passage 23 is conducted. The upper end of the plug 3U has crossed slots, as shown at 33, so that the piston 29 cannot entirely close communication between the passage 23 and the open upper end of the passage 3|.

Adjustable valves 35 and 36, controlled by adjusting knobs 31 and 38 respectively, permit adjustment in the amount of uid that may flow through the two. branch passages, permitting a complete closure of the branch passage 25, as shown in Fig. 2.

The upper end of the piston 29 engages the base of a valve stem 39 which is slidably operable in a guide 49 shown in Fig. 6. At its upper end the valve guide 49 has a boss 4I provided with transverse slots 42 which permits the fiow of fluid at all times from the inlet passage 23' to the passage 24. The upper end ofthis boss en.- gages a retaining plug 43 threaded in the top of the valve housing withasealing washer 44 interposed between the head of the plug andthe valve housing to seal against fluid leakage. A bored passage inthe plug loosely receivesthe,` upper end` of the valve stem 39when the valveis moved upwardly from the retracted position shown in Fig. 2. A spring 43 is interposed between. the

lowerend ofzthe'valve guide t9/andthe upper end of the lpiston 29 to urge the piston yieldingly in a downward direction so'that with no flow of fluid taking place the lower endof the piston contacts theupper slotted end .ofthe plug 36.

When fluid is supplied under pressureto the pressure chamber 2l, the pressure exerted on the lower end of the piston causes the piston to move upwardly thus moving the valve 39 upwardly and opening. communication from. the inlet passagev 23 through` an annular valve passage 46. to branch passages! 41 in the valvev guide 49. Thesebranch passages il?` are inV constant communication with a relief passage 48 extending to the atmosphere as shown in Fig. 5; Thus the greater` the pressure existing inv the pressure chamber 21, the more the valve 39 will be raised and the greater will be the flow thatby-passes fromV the inlet 23 to the relief passage 48.

The operation of they automatic valve is as follows: With the fluid connection I8 extending to a gauging nozzle and with fluid under pressure supplied. to the pressure regulator I2, valve 35 ybeingy retracted to open the passageV to the branchv passage 25, all of the flow throughthe fiowtube I3-comingto the coupling I 5 travels out through the passage 3l and the height of the 'float Id-indicatesthe amount of ow taking place through the passage 3i. None of the air` entering the intake passage 23 is by-passedv to the dischargeA passage 49 under these conditions, since the valve 39 remains in its lowered position, entirely cutting out flow from the intake 23 to the relief passage 48. Thevalve remains lowered because the pressure on the upper side of the piston 29 is the same as the pressure applied to the lower side of the piston, or substantially so. However, where an. increased movement of the oat is desired, or in other words, to increase the amplification factor ofthe ow gauge, the valve 35 is moved to close the branch passage 25 and the pressure exertedA on the lower side of the piston raises the piston against the force of the spring 45 and moves theV valve upwardly so that some of the air is relieved from the inlet 23 through valve passage 43 directly to the atmospheric vent passage 48. A slight increase in the pressure existing in the pressure chamber 27, produced by a decrease in the flow through connection I8 for example, raises the piston and the valve to increase the rate of flow through the discharge passage 48 so that small changes in the rate of iiow through the connection I8 have a much greater effect in the rate of flow of fluid through the coupling I 5 and through the iiow gauge. A small increase in the flow taking place through connection I8 and the resulting decrease in pressure below the piston causes a comparatively large downward movement of the float I4.

By changing the setting of the valve 36 the level of the float may be changed to bring it within the proper range of the iiow tube for any given condition.

By reason of the pressure responsive valve which controls the flow of iiuid to the atmosphere and to the gauging nozzle in an automatic manner, wide variations in the rate of low through the flow gauging device can be caused by comparatively smalll variations in the flow through the gauging nozzle, thusgreatly amplifying the sensitivity of the gauging instrument. It should also be notedV that it is not necessary to-have theuid pressure supply for the pressure chamber come from the same pressure regulated system in which the flow gauging means is Ycon tained. However in the particular kembodiment of the invention illustrated the coupling I5 and the inlet passage 23, flow through which iscontrolled by the pressure responsive valve 39- also, constitute the. source of fluid supply at substantially constant pressure for the operation ofthe valve .39.

In the particular embodiment of the invention shown, where the device is for checking surface nish, the fluid connection i8 as.V previously mentioned isv connected to'a gaugehead 2l, on which is cemented a ring or'pad- 5I)V of rubber or other suitable yielding material, and cemented or xed to the pad 50 is a thin exible centrally perforated disc or ring 5I., preferably of'steel of afewthousandths of 'an inch in thickness so that when it is applied.. tothe workpiece it will conform to the general contour or general waves in the face of the workpiece. However, the smooth finished surface on the side ofthe ring 5I that is applied to thev workpiece, beingof hard material, will form tiny passages between the gauging surface and the surface to be gauged, so that the roughness of the surface, gaugedwill control the vamountV of ud escaping.

Thefwork head- 27| has a ange 52 normally carried against an inturned flange 53 ina sleeve 54, there. being sufficient clearance between. the

outer surface of. flange 52 and the inner diameter of sleeve 54vso that some angular movement or tilting of the work head2! can take place within the sleeve. Within the sleeve is an abutment ring 55 heldV up. against a locating screw 56.Y by a tensionspring. 5l. The lower end of the spring 5l urges the work head 2I downwardly holding it normally against the flange 53-in the position shown in Fig. 3. Slidably arranged on the outside of sleeve 5ft is a guardv sleeve 58. normally held in. a projected` position as showny in Fig. 3 by a spring 59. A pair of stopscrews 60 thread.- ed in the guard sleevev 5i?` operate inA longitudinally extending slots 6I in the sleeve 54. Spring 59 exerts only a light pressure on the guard sleeve so that when the lower end of .the sleeve is applied to the work the sleeve-is easily pushed upwardly permitting. the application4 of the gauging surface to the surface to begauged'.

As the operator presses downwardly on the handle 62, which is fixed t the upper end of the sleeve 54, pressure is applied through the spring Sito exert a predetermined constant pressure of the head 2l against the work, since the spring 51 is interposed between the handle and the work head. In its gauging position the flange 52 is spaced from the stop flange 53, as will be apparent from the position of the parts shown in Fig. 4. The tilting action of the work head within the guide sleeve 54 insures complete engagement of the gauging surface with the work even if the axis of the sleeves 54 and 58 may not be exactly perpendicular to the surface gauged.

The distance between the passage in the gauging sheet 5l and the circumference of that sheet and the pressure of the fluid supplied to the passage in the gauging head control the amount of fluid leakage taking place along the tiny cracks and c'revices of the workpiece gauged, the pad 50 preventing loss of pressure as the fluid travels to the surface t0 be gauged. Since the sheet 5| is comparatively thin but of comparatively rigid material, it is flexible enough so that it will accommodate itself to any small changes in curvatremely accurate readings of surface finish can f be obtained by direct comparison with a master or surface of known micro finish.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited t0 this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

l. A gauging head adapted for use with a flow measuring device, for a gauging operation by fluid flow between a surface to be gauged for surface finish and a gauging surface, comprising a member having a fluid passage and having a discharge opening, a yielding pad secured to said member around the discharge opening and a thin flexible sheet of metal secured on said pad and having a smooth perforated gauging surface for application to the surface to be gauged.

2. In a device for gauging surface finish by fluid flow between the surface to be gauged and a gauging surface, a gauging head having a fluid supply passage, a thin flexible sheet of material having a passage therethrough and provided withY a smooth gauging surface for application to the surface to be gauged, and a pad of yielding material secured at one side thereof to the gauging head adjacent the fluid supply passage and secured at the other side thereof to said sheet of material and forming an air conduit between said head and said sheet, said sheet being sufficiently thin to conform to the general contour of the surface gauged merely by application of manual pressure exerted through said pad.

3. In a device for gauging surface finish by fluid flow between the surface to be gauged and a gauging surface, a gauging head having a fluid supply passage, a thin flexible sheet of material having a passage therethrough and provided with a smooth gauging surface for application to thesurface to be gauged, a pad of yielding material securing said sheet to said head and forming'a'n air conduit between said head and said 6 sheet, the thinness of the said sheet being such that it will conform to the general curvature of the surface gauged and a spring pressed guard means about said head for the protection of said sheet.

4. A gauging head adapted for use with a flow measuring device, for a gauging operation by fluid flow between the surface to be gauged and a gauging surface, comprising a member having a fluid passage and having a discharge opening, a rubber ring cemented to said member around the discharge opening and a thin metal disk cemented on said pad and having a smooth centrally perforated surface for application to the surface to be gauged, said disk having flexibility to conform to the general contour or curvature of the surface gauged.

5. In a device for gauging surface finish by fluid flow between the surface to be gauged and a gauging surface, a gauging head having a fluid supply passage, a thin flexible sheet of hard material having a passage therethrough and provided with a smooth perforated gauging surface for application to the surface to be gauged, a pad of yielding material securing said sheet to said head and forming an air conduit between said head and said sheet, and means for exerting a predetermined pressure on said gauging head.

6. A fluid operated gauging apparatus for gauging surface finish and adapted for connection to a fluid pressure source, comprising a flow gauge, means providing a controllable relief passage, a fluid connection from the flow gauge to the relief passage on the down stream side of the flow gauge, a work head having a fluid passage,

means for supplying fluid under pressure to said fluid passage, a thin flexible apertured hard surfaced sheet adapted for application to a surface to be gauged for surface finish, a yielding pad having a central aperture and secured between said sheet and work head, the aperture in said pad and sheet communicating with the fluid passage in the work head, a valve operable to control flow through said relief passage and valve controlling means responsive to changes in fluid pressure in the Work head passage for automatically controlling said valve such that small changes in fluid flow through the work head cause amplified changes in fluid flow to said relief passage.

7. A fluid operated gauging apparatus for gauging surface finish and adapted for connection to a fluid pressure source, comprising a flow gauge, means providing a controllable relief passage, a fluid connection from the flow gauge to the relief passage, a work head having a fluid passage, means for supplying fluid under pressure from the flow gauge to said fluid passage, a thin flexible hard surfaced sheet adapted for application to a surface to be gauged for surface finish, a yielding pad between said sheet and work head, said pad and sheet having passage in communication with the fluid passage in the work head, a handle, a spring between said handle and said work head for applying a predetermined force to said work head and valve means responsive to changes in fluid pressure in the work head passage for automatically controlling said relief passage and thusl affect the flow gauge.

8. In a device of the character described, a flow gauging means adapted for connection to a source of regulated fluid pressure, said means having a member responsive to changes in fluid flow, a pressure chamber in communication with said gauging means and on the down stream 7 side thereof and having a discharge; opening; for the discharge of. uid-passingthe gauging means, and a. valveV automatically operable. in accord.- ance with the pressure in the pressure chamber for controlling the ow of fluid from said pressure chamberthrough said discharge opening,

9'; In` a device ofi the character described, a ow gauging means adapted for connection to a controlled. fluid pressure sourceY and having a member responsive to changes. in uid flow, a gauging` headl having a passage andV having a discharge. opening;` means: for supplying uid under; pressure to saidy passage, means providing a relief. passage forA uid passingV said gauging means, and' a valve automaticallyl operable in accordance with changes in the pressure in said gauging head passage for controlling the flow of iluid'from-,said.gaugingmeans tosaid relief passage.

1l).V In. adevice. of the character described. for increasing; the sensitivity of a ow gauging means, a valvehousing having a supply passage adapted for-connection to a flow gauging,vv means, a. pressure chamber provided with aV discharge opening, means for supplying said chamber with fluidunderpressure, a valve automatically oper ablein accordance with the-pressure in the pressurechamber, said housing having a relief passagecontrolled by said valve forcontrolling the flow of iluid? from said supply passage.

lil.` A gauging device comprising a ow gauging means adaptedv for connection at the supply side thereof to a source of regulated pressure, meansfat thefdown-stream side of said flow gang;- ing. means providing a discharge passage for the relief' ofv fluid. passingv theV gauging means, a relief valve operable. to control the: flow through said discharge passage, a. gauging head having. a passage for iiuidpassng to a gauging-zone, means for-supplying fluid under lpressurev to said gauging headJ passage, pressure sensitive meansv responsive to theV changes in pressure insaid gauging head passage, and a connection between said p ressure sensitive means and said relief valve for automatically controlling said valve; so that small changes, in uid ilow in the gauging head passage produce amplied changes in the uid flow through the flow gauging means.

l2; A gauging device comprising, a` gauging head, a pressure regulator, a conduit for supply,-

REFERENCES CITED The following referencesV are of record inthe le of this patent:

UNITED STATES PATENTS Number Name DateV 2,150,266 Cotner Mar. 14, 1939 2,375,600 Wattebot May- 8, 1945 2,403,897 Aller July 16 1946 2,417,988 Mooney Mar. 25, 1947 2,420,394 Gilman MayY 13, 1947 FOREIGN PATENTS Number Country Date` 577,294 Great Britain. May 13, 1946 

